1. Field of the Invention
The present invention relates to a process for preparing organosilicon compounds having organyloxy groups in the presence of a catalyst system comprising a zinc chelate and an amine and/or alcohol, and also to their use in compositions which crosslink at room temperature.
2. Background Art
The preparation of siloxane compounds from silanol and alkoxysilanes in the presence of titanates, optionally with amines, has been known for a long time. Reference may be had, for example, to U.S. Pat. No. 3,504,051. To prepare alkoxy-terminated polydimethylsiloxanes, the combination of various acids with amines has also been described, e.g. organic acids with amines in FR 2,604,713, Lewis acids with amines in U.S. Pat. No. 4,515,932 or formic acid with amines in EP-A 304 701. U.S. Pat. No. 5,055,502 describes the use of zinc chelates as a catalyst for the preparation of alkoxy-terminated polydimethylsiloxanes. All these preparative methods have certain disadvantages: the reaction times are usually very long, thus requiring temperatures which are higher than the temperatures which are usually employed, or the required catalyst concentrations are so high that the catalysts have to be removed or deactivated in an additional step. Many systems tend to suffer from yellowing or are stable only in particular formulations.